ER70S-3: With a lower deoxidant content than ER70S-2, ER70S-3 is better suited for welding cleaner, non-rusty surfaces. While it performs adequately in bright, polished conditions, it shows more slag formation and porosity when used on rusted or dirty base metals. Its lower deoxidant content results in a higher oxygen concentration in the weld pool, which can affect penetration and bead width.